1. Field of the Invention
This invention relates to containers, more particularly to container closures.
2. Prior Art
In recent years there has been an emphasis on providing containers with closures that are resistant to opening and which, when opened, provide an indication of prior opening. A known type of such closure includes a cap structure or assembly which has a portion that interfits or indexes with a part of the container in such a way as to prevent removal of the cap. The cap portion is attached to the main body of the cap through frangeable connections which allow the removal resistant portions of the cap to be severed from the remainder of the cap by breaking the frangeable connections. One known way of constructing such caps is to construct a screw-on cap having a skirt with a inner diameter raised portion adjacent the bottom of the skirt and with the container formed with an outer diameter raised bead such that when the cap is screwed onto the container the two raised portions overlap preventing the cap from being unscrewed. By forming the cap raised portion on a part of the cap skirt connected to other parts of the cap through frangeable connections, it is possible to separate the anti-removal feature from the remainder of the cap thereby allowing the cap to be removed. A disadvantage with this particular type of construction is that a portion of the cap is, in fact, removed and discarded such that it is not always easy to detect whether or not the container has been previously opened due to the fact that the frangeable anti-removal portion has been discarded and the remaining portion still functions as a normal cap. Another disadvantage with this type of construction is that it has to be put on by automatic capping machinery as a part of the regular threading on process and the frangeable connections can be easily broken during factory capping. Another disadvantage, particularly associated with that type of closure where the anti-removal portion remains on the container or on the closure cap, is that it is often difficult to break the frangeable connection.
Other types of tamper evident closures include the use of overcaps which are secured either to a nonremovable closure cap or to a portion of the container and which, when in position, prevent access to the closure cap. While it has been suggested to make such overcaps in such a manner as to include frangeable connections facilitating intentional removal of the overcap, such assemblies have not generally been easily assembled by standard manufacturing assembly techniques on container filling lines.
It would therefore be an advance in the art to provide an improved tamper indicating closure assembly adaptable to substantially all types of closures, wherein the structure readily gives indication of previous opening and wherein the assembly can be automated and the frangeable connection easily broken.